Plans for a major new international airport along the Severn Estuary in south Wales are unlikely to go ahead, the UK Government said.

It has outlined options for expanding airports and runways, with passenger numbers expected to double in the next 20 years.

Private developers Severnside Airport Plc claim they have �2bn ready to build Wales' second major airport near to Corus' Llanwern steelworks close to Newport.

Cardiff International Airport could be expanded

But Transport Minister Alistair Darling said their proposal was "extremely unlikely" to get the green light and would only go ahead if airports at Cardiff or Bristol closed down.

He said an increase in capacity for the existing facility in the Welsh capital was likely to figure in a White Paper released next year, as politicians look to handle a massive increase in flights.

Members of the public will be able to offer views on the suggestions before the government finalises its policy next year.

Cost to environment

The Severnside plan has been mooted since 1998 and actively pushed by the developers.

The former Gwent County Council had previously granted planning permission on the series of mudflats between Newport and Caldicot.

Mr Darling will be addressing MPs on Tuesday

But Friends Of The Earth campaigners in Wales said the project would have a big detrimental impact on the local environment, tampering with legally protected wildlife.

They say a plan to build the airport's main runway on a man-made island just off the coast would wipe out 780 acres of mudflats.

Severnside Airport Plc chief executive Michael Stephen had eealier said he was certain his plan would be included in the government's future consultation.

Cardiff development

Instead, the Cardiff facility's terminal and aircraft stand facilities are expected to be earmarked for a big overhaul.

The modest facility at Rhoose is relatively underused and has already been promised improved road links with the city, the M4 motorway and the rail network - connections which have hampered its development.

Mr Darling also told MPs his White Paper report would consider beefing up domestic flights within Wales where there would otherwise be long road journeys.

Regular north-south flights have already been mooted by the Welsh Assembly as a means of people movement and cultural migration.

The minister also welcomed low-cost airline bmibaby's recent news it was locating at Cardiff International Airport, saying the facility was now becoming "a major centre".